Having ‘diverticulosis’ means small pouches have formed in the wall of your large intestine (colon). Having ‘diverticulitis’ means these pouches have become infected or inflamed. While these are related conditions, they sometimes need different dietary approaches, especially when it comes to fibre.
Getting plenty of fibre is good for your gut health, and it can help with diverticulosis. But if you’re having a tricky diverticulitis flare-up, doctors may recommend a low-fibre, liquid diet in the short term to ease the pressure on your gut.
In this article, we’ll compare diverticulosis and diverticulitis, spotlighting the differences in symptoms, complications and treatments. We’ll then discuss what to eat during a diverticulitis flare, including any foods to avoid.
What’s the difference between diverticulosis and diverticulitis?
Diverticulosis, where small pouches develop in the wall of your large intestine, is a common occurrence. Diverticulitis is one possible complication of diverticulosis.
Let’s break down some of the terms you might see related to these conditions:
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diverticulum: a small pouch that bulges out from the wall of your large intestine
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diverticula: more than one diverticulum (or pouch)
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diverticulosis: the presence of diverticula in your large intestine
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diverticulitis: when diverticula become infected or inflamed
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diverticular disease: a term for all the illnesses related to diverticula
We’ll use ‘diverticular disease’ to describe having both diverticulosis and diverticulitis together.
Now let’s look at the main ways diverticulosis and diverticulitis are different.
Diverticulosis
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Symptoms: Most people with diverticulosis have no symptoms. Some may experience mild or intermittent lower tummy pain, cramping, changes in bowel habits and occasional blood in their poo (without pain).
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Prevalence: It affects 5–45% of people in the Western world and becomes more common after the age of 40.
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Complications: Inflammation or infection can lead to diverticulitis.
Diverticulitis
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Symptoms: Fever, pain in the lower left part of your tummy (which can be severe), changes in bowel habits, nausea, diarrhoea, constipation, bloating and blood or mucus in your poo. The pain may get worse after eating and better after pooing or farting.
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Prevalence: Around 4% of people develop diverticulitis in their lifetime.
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Complications: A buildup of pus in the bowel, a blocked bowel, a hole in the bowel or an opening leading from the bowel to another organ, like the bladder.
Which is more serious: Diverticulitis or diverticulosis?
Diverticulitis is more serious than diverticulosis, as it can have severe complications requiring urgent treatment.
Because diverticulosis is mostly symptomless, many people don’t realise they have it. It doesn’t require treatment when this is the case, but doctors may recommend paying attention to your diet to reduce the risk of complications.
You should contact a doctor any time there’s blood or mucus in your poo.
Why diet and fibre matter in diverticular disease
Because diverticulosis and diverticulitis affect your gut, what you eat can play an important part in managing these conditions.
In general, the NHS recommends slowly increasing the fibre in your diet if you don’t eat much of it. It’s important to drink plenty of water, as water helps fibre move through your gut effectively.
Fibre is great for your gut health. It’s a form of food for the microbes living in your gut – collectively called your gut microbiome. When these microbes break down fibre, they produce compounds that help keep your gut lining healthy and manage inflammation.
If you have diverticulosis, fibre can help reduce spasms and pressure in your large intestine, factors that can cause symptoms.
In one older study, people eating 25 grams of fibre a day had a 41% lower risk of needing to go to hospital for diverticulitis, compared with those eating less than 14 g of fibre a day.
There’s also early evidence of a relationship between an unbalanced gut microbiome and diverticulitis. Still, more wide-ranging research is needed to support these initial findings.
We should all aim to eat 30 g of fibre a day. If you’re looking for inspiration, check out dietitian Laura Tilt’s guide to 30 g, which is complete with meal plans.
However, as we mentioned above, some diverticulitis flare-ups with serious symptoms warrant a different approach, especially if they require more involved forms of treatment.
Diet during a diverticulitis flare
The best foods to eat when you have diverticulitis will depend on how severe it is and if there are complications.
In most cases, doctors treat diverticulitis with antibiotics and pain relief medications, such as paracetamol. Depending on your symptoms, they may also provide laxatives and drugs to help with cramping.
When the diverticulitis flare is not serious, this treatment tends to do the job. And in these instances, continuing with a high-fibre diet is usually the way to go.
There’s no evidence that reducing your fibre intake during an uncomplicated bout of diverticulitis can provide any benefits.
If a diverticulitis flare is more serious, however, or your doctor suggests more involved tests and treatments, like a colonoscopy or bowel surgery, you may need to change your diet.
The doctor may recommend a low-fibre diet (also known as a low-residue diet) to minimise irritation.
Low-fibre diets should be a short-term change to make it easier for doctors to do certain procedures. Once they’re done, you can gradually reintroduce fibre into your diet.
Learn more about healthy low-fibre foods.
Meal and recipe ideas for diverticular disease
There are three dietary approaches to diverticular disease:
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a high-fibre diet for diverticulosis and uncomplicated diverticulitis
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a short-term, low-fibre diet for complicated diverticulitis ahead of treatment
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gradually reintroducing fibre back into your diet
High-fibre diet
A high-fibre diet is recommended for people with diverticulosis.
For some cases of diverticulitis, doctors may recommend a temporary low-fibre diet, followed by a gradual increase in fibre. As we mentioned earlier, the goal is generally to eat 30 g of fibre a day.
You can spot some high-fibre foods by looking at their nutrition labels; if a product contains 6 g of fibre or more in every 100 g, it’s a high-fibre food.
Here are some delicious, gut-friendly recipes that pack a hearty fibre punch:
Discover other recipes in our article on easy high-fibre meals, or these in-depth articles on high-fibre breakfasts and lunches.
Low-fibre diet
A low-fibre diet is only useful as part of a treatment for complicated diverticulitis or when you’re preparing for a diagnostic test, like a colonoscopy.
Reducing the fibre in your diet limits how much undigested food moves through your gut. Your bowels have less work, and doctors can have a clearer look at your colon during tests.
Some doctors may even recommend a temporary liquid diet to reduce the strain on your gut.
Here are some low-fibre liquid soup recipes that are gentle on your gut:
For more suggestions, check out our article on easy-to-digest meals.
Reintroducing fibre
Once your doctor gives you the go-ahead, you’ll want to slowly bring more fibre into your diet. It’s important to do this gradually.
‘Switching from a low- to a high-fibre diet in one swoop is likely to result in lots of gas and discomfort, and it’s a surefire way to put you off a change which has lots of benefits in the long term’, says Tilt.
For the first week, try eating a small amount of fibre once a day, such as a portion of fruit or veggies with the skin on.
If this feels OK, try to increase your fibre a little bit more: add a portion of wholemeal carbs (such as brown rice or whole-grain bread) once a day for the next week.
While you’re reintroducing fibre, be sure to drink plenty of water. Your body needs this to help the fibre move through your gut and keep your poo soft.
Learn more about fibremaxxing, the TikTok trend of maximising the fibre in your meals.
Frequently asked questions
Let’s look at some questions people have asked about the best diet for diverticulosis and diverticulitis.
Is it safe to eat nuts, seeds and popcorn with diverticulosis?
Yes, it’s safe to eat nuts, seeds and popcorn with diverticulosis.
Let’s bust a myth: for many years, people have worried that small foods like these could get stuck in diverticula pouches and cause infections.
But there’s no evidence that these foods increase the risk of diverticulosis or related complications. In fact, these high-fibre foods could even help reduce your risk of diverticulitis over time.
Does red meat increase the risk of diverticulitis?
So far, there’s not enough research to suggest that red meat on its own can increase the risk of diverticulitis.
The suggestion that red meat could increase your diverticulitis risk is based on research looking at dietary patterns.
These studies have found that a Western dietary pattern (high in red meats, refined grains and high-fat dairy) is associated with a higher risk of diverticulitis, but a diet high in fruits, vegetables and whole grains is associated with a lower risk.
These findings don't necessarily mean that red meat can lead to diverticulitis. They do suggest that a high-fibre diet can make a difference, however. So if you do eat red meat, make sure you’re still eating lots of plant foods to keep your gut happy.
Do probiotics help with diverticulitis?
The jury is still out on whether probiotics can help with diverticulitis.
As the research is currently inconclusive, the NHS can’t recommend them to help treat this condition.
Some initial studies have seen promising results: certain Lactobacilli probiotics seemed to reduce bloating and pain for some people with uncomplicated diverticulitis. However, experts need more research before they can draw conclusions.
Learn more about live, friendly bacteria and your gut health.
Summary
Diverticulosis and diverticulitis are two forms of diverticular disease that affect your large intestine. Diverticulosis is when small pouches form on your colon’s lining, and diverticulitis is when these pouches become infected or inflamed.
In most cases of diverticular disease, a high-fibre diet is best. Eating plenty of fibre supports your gut health, and research suggests that it can reduce the risk of complications.
More severe cases of diverticulitis may require switching to a low-fibre diet temporarily to help with treatment or further investigations.
Your doctor will let you know if you should change your diet to help manage diverticular disease.
To learn more about other gut health topics, visit Symprove’s Gut Hub.
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Dietary fibre in gastrointestinal health and disease. Nature Reviews Gastroenterology and Hepatology. (2020). Link.
Diverticular disease and diverticulitis. (2023). Link.
Diverticulosis. StatPearls. (2023). Link.
Gut microbiome composition and metabolic activity in women with diverticulitis. Nature. (2024). Link.
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How to get more fibre into your diet. (2022). Link.
Nut, corn, and popcorn consumption and the incidence of diverticular disease. JAMA. (2008). Link.
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